1. Technical Field
The present invention relates to a method of manufacturing a semiconductor device, a substrate processing method, and a substrate processing apparatus.
2. Related Art
Conventionally, when an Si film is formed by a CVD method, forming a non-doped Si film using SiH4 (monosilane), Si2H6 (disilane) or the like as a reaction gas or forming a P-doped Si film by adding PH3 (phosphine) or a B-doped Si film by adding B2H6 (diborane) or BCl3 (boron trichloride) in SiH4 or Si2H6 as a reaction gas, respectively, in order to diffuse B (boron) or P (phosphorus) as an impurity into a film, is performed.
When the Si film is formed at a low temperature of 400° C. or less, Si2H6 is generally used in order to form the non-doped Si film. When Si2H6 is used to form the non-doped Si film, a film thickness of the peripheral edge of a wafer (substrate) is rapidly increased and film thickness uniformity (in-plane film thickness uniformity) in the wafer is significantly poor. Furthermore, in terms of the film thickness in a batch, the film thickness of a bottom (boat bottom) is decreased and the film thickness uniformity between the wafers (inter-wafer film thickness uniformity) is also poor. For these problems, by adding B in SiH4 and using a catalytic effect of B, it is possible to lower the temperature to the equivalent of that of the non-doped Si using Si2H6 and significantly improve the film thickness uniformity within the wafer. However, even when a film is formed by using this means, improvement in inter-wafer film thickness uniformity is insufficient. In particular, when using SiH4 as the reaction gas, since it is necessary to add B therein, it is difficult to lower the B concentration in the film, and B may react with SiH4, as a dopant, to become a B-doped Si film.
Since the wet etching rate of the B-doped Si film is significantly poor as compared with the non-doped Si film, there is a problem that raising the efficiency of the device manufacturing process becomes difficult. (For example, see JP 2012-204691 A)